Timing mechanism for breakerless ignition systems

ABSTRACT

In an ignition system for use with spark ignited engines, a timing mechanism for manually advancing or retarding the firing point of the cylinders in the engine.

United States Patent Henderson 3,886,916 June 3, 1975 DRR ooooooC7 444M4 N 333 33 222M22 ill 1.1 3 2 l Falge et 9/1969 Burson 12/1969 Piteo3/1974 Reddy........:::::::::::::::..

HL n 8U CH 7 23 6 77 9 99 M NH 6 62 497 67 37403 0054769 2600679 3 4 39333333 Robert McDougall Henderson,

Colt Industries Operating Corp., New York, NY.

Aug. 20, 1973 Appl. No.: 389,680

Primary ExaminerManuel A. Antonakas Assistant Examiner-James David Liles[22] Filed:

Attorney, Agent, or FirmLeo J. Aubel Related US. Application Data [63]Continuation -in-part of Ser. No. 242,324, April 10,

1972, abandoned.

m e s m u S m B 1 A m e n a 5 n I 2 OA 0/ 4 1 6 W2 4 2M R31 7 n 1H8 104y NH 3 n "2 1 mmh "c r "a e US l h C IM .t e Umm .11] 2 8 555 [[1 gines,a timing mechanism for manually advancing or retarding the firing pointof the cylinders in the engi 123/149 C, 149 D, 117 R 3,145,324 Race123/148 E 6 Claims, 17 Drawing Figures PATENIEU JUN 3 1915 3.8 836L916TRIGGER PULSE f K] I N (a) TRIG GER PULSE Q @2 gang-22 37 F L s; [L

130 2 C YL PATENIEDJUN 3 ms SHEET wclz AT ONE SPEED COMBINATION ADVANCEAND ADVANCE HIGH sPEED AT ONE POSITION OF ADVANCE ADVANCE SPEED COILVOLTS SPE/ED J g/05 N BM in P RS O F ADVANCE TIMING MECHANISM FORBREAKERLESS IGNITION SYSTEMS CROSS-REFERENCE TO RELATED APPLICATION Thisapplication is a continuation-in-part of application Ser. No. 242,324,filed Apr. 10, 1972 now abandoned.

BACKGROUND OF THE INVENTION The invention relates to ignition systemsfor spark ignited engines and is directed particularly to an advance orretard mechanism. Hereinafter, the term timing mechanism will also beused to refer to the advance and retard operations and to the associatedmechanism respectively.

Various breakerless ignition systems have been disclosed in the priorart wherein mechanical breakers are replaced by solid state electronicswitches controlled by a trigger signal, which are generally morereliable than the mechanical systems and are less subject to mechanicalwear and deterioration.

Various prior art advance mechanisms generally rotate the sparkinitiation means relative to the piston and crank shaft position whenchanging the advance characteristics of the associated engine and wiresconnecting the rotating trigger mechanism to the stationary portions ofthe engine are thus continuously flexed. Thus, it is desirable toprevent movement or flexing of the wires to prevent eventual damage andbreakage.

The present invention is directed to a breakerless ignition systemincluding a simplified and manually adjustable ring mechanism whichpossesses the feature of maintaining an essentially constant orcontrolled air gap between each pole piece mounted in the timing ringand the associated triggering coil core, and can provide the feature oflowering the triggering coils output voltage when the timing ring ismoved by the throttle to a high speed operating condition. In addition,the timing ring mechanism of the invention eliminates flexing of theassociated wires.

The foregoing and other features, objects and advantages of theinvention will be apparent from the following more particulardescription of preferred embodiments of the invention, as illustrated inthe accompany-' ing drawings, wherein:

DESCRIPTION OF THE DRAWINGS FIG. 1 shows a plan view of a rotor assemblyincluding an advance mechanism in accordance with the invention;

FIG. 2 is an isometric view of one embodiment of a timing ring inaccordance with the invention;

FIG. 3 is a plan view of a portion of a rotor assembly utilizing thetiming ring of FIG. 2.

FIG. 4 shows curves useful in explaining the operation of the inventiveassembly;

FIG. 5 shows a schematic diagram of an electronic circuit suitable forelectrical connection with the assembly of FIGS. 1, 2, and 3.

FIG. 6 shows a plan view of another embodiment of the advance mechanismin accordance with the invention;

FIG. 7 is an isometric view of a pole piece, a rotor, and a core pinsuch as employed in FIGS. 1, 2, and 3 to better show the structuralrelation of the elements;

FIG. 8 shows a pole piece in a T-shape;

FIG. 9 shows a structure wherein the pole piece comprises a verticalmember and the core pin comprises a T-shape;

FIG. 9B shows the air gap between the pole piece and a core pin;

FIG. 9C shows a T-shape pole piece mounted vertically above the corepin;

FIGS. 10A and 108 show the positioning of the pole pieces for use with athree cylinder engine;

FIG. 11 shows curves useful in explaining the operation of an assemblysuch as in FIGS. 1, 2, and 3;

FIG. 12 shows the different peripheral positioning of a pole piece toprovide either uniform, increasing, or decreasing air gaps;

FIG. 13 shows curves useful in explaining the operation of the polepieces of FIG. 12; and,

FIG. 14 illustrates the peripheral position or relationship of the polepieces for use in either 2, 3, or 4 cylinder engines.

DESCRIPTION OF THE INVENTION Referring to FIGS. 1 and 2, an ignitionassembly 11, in accordance with the invention, includes a pulser rotor13 mounted for rotation on a shaft, not shown which is attached to aconventional flywheel, also not shown. The pulser rotor 13 is formed ofa magnetic material and comprises a unique construction wherein theperiphery 15 of the rotor 13 is formed in the approximate configurationofa convolution of a spiral. The pe riphery 15 of pulser rotor 13includes a peak or maximum diameter point A and a minimum diameter pointB, which two points A and B are joined by an inwardly angled surface 17.A pair of diametrically spaced permanent magnets, 21 and 23, eachcomprising a foreshortened semi-circle and having a magnetization asshown, are suitably mounted on rotor 13. Air spaces 25, and 27 may beformed between the ends of the magnets 21 and 23. The foregoing magnetsystem could comprise other suitable alternatives such as a single ringmagnetized in a radial direction.

A pair of diametrically spaced triggering coils, 29 and 31, are mountedon the circular casing 14 of the assembly 11. The coils 29 and 31include respective trigger coil cores 33 and 35.

A timing ring 12 which may be an aluminum casting is movably mounted ona suitable support 22 in casing 14. The timing ring 12 includes athrottle linkage 18 which is connected to a manually adjustable handleor knob (not shown) to permit movable rotatable adjustment of timingring 12, as will be explained. In one embodiment, timing ring 12 ismovable about an approximate arc of about 36 indicated by the arrowedline 20 in FIG. 1.

Timing ring 12 is mounted to provide an arc gap. as at 26 and 28 betweenthe inner surface of the ring and the outer surface of the pulser rotor13. An air gap 34 and 36 may also be provided for mechanical clearancebetween the trigger coils 33 and 35.

Timing ring 12 includes similar magnetic pole pieces. (two Lshaped polepieces being shown and numbered 37, 39 in the embodiment of FIG. 1),which are positioned intermediate the associated coils 29 and 31 androtor 13, as will be explained in more detail hereinafter. The polepieces each include a pole shoe 47 and a flux conductor section 49, aswill be explained, (see FIG. 2). As indicated in FIG. 1, one or morepole pieces could be utilized in the inventive assembly. with two 3 polepieces 37 and 39 being shown in FIG. 1 and four pole pieces 37, 39, 41,and 43 being indicated in FIG. 2.

The timing ring 12 is movable between two extreme positions as indicatedby the arrow 20, and regardless of the position of ring 12, a portion ofthe pole shoe 47 is always adjacent to the core of the associatedtrigger coil; for example, shoe 47 of pole piece 39 is always ad jacentcore 35 of trigger coil 31 regardless of the position of the ring 12;within limits of timing ring travel.

Thus, the relative position at which the maximum diameter point A of therotor 13 passes adjacent to axially extending flux conductor 49 isdependent upon the position of the timing ring 12, which is adjustableby a throttle linkage to thereby control the timing (advance or retard)of the engine.

As is known, when the throttle is actuated, the speed of the engineincreases and thereby causes an increase in the speed of rotation ofrotor 13 and an increase in the voltage generated in trigger coils 29and 31. Also, as the rotor 13 is rotated at a higher speed, the periodof the cycle is shortened. Therefore, the selective positioning of thepole pieces 37 and 39 varies the time at which the trigger pulse isgenerated; a normal variation being approximately 36 of the input cycle;that is, for a given speed and given output waveform, movement of thepole pieces 37 and 39 causes the time of the triggering pulse to bechanged.

The coils 29 and 31 are connected to a suitable electronic circuit, suchas, for example, shown in FIG. wherein the coil 29 is connected througha diode 57, a triac 59 and the primary winding 61 of a transformerignition coil to capacitor 63. The secondary winding 65 of the ignitioncoil is connected to an associated spark plug, indicated by thearrowhead P.

The particular construction of the rotor 13 of FIGS. 1 and 2 providesthe features and advantages disclosed and claimed in the US. Pat.application Ser. No. 220,065 filed Jan. 24, 1972, in the name of K.Reddy entitled: Pulser Rotor For Ignition Systems" and assigned to thesame assignee as the present invention. As disclosed in application Ser.No. 220,065, when the rotor 13 is rotated in a first direction(clockwise direction in FIG. 1), a suitable unidirectional triggeringpulse (say of a relative positive polarity is provided for energizingthe associated spark plug. However, should the rotor 13 be rotated in arelative reverse direction, the pulses developed will be of minimalamplitude in the positive polarity and insufficient to energize theassociated spark plugs.

Referring again to for example FIGS. 2 and 3, the pole pieces 37, 39,41, and 43 are formed in essentially an L-shape with a peripherallyextending pole shoe, generally labeled 47, which is formed to conform tothe radial periphery of the timing ring 12, and an axially fluxconductor section, generally labeled 49. As shown in FIG. 2, the polepieces may be embedded in suitable recesses in timing ring 12. In FIG.1, the flux conductor section 49 is approximately the same thickness asring 12, and the shoe 47 is approximately one half the thickness of ring12, while in FIGS. 2 and 3, the pole pieces 37, 39, 41, and 43 areapproximately three-quarters of the thickness of ring 12.

An additional ring or flange 12A of a flux conductive material such asof aluminum is mounted on an edge of ring 12 and functions as a noisereducing shield by shunting away from the trigger coils any spuriousflux which may be generated in the system. Ring 12A functions as amagnetic shield for external circuits; and, in effect provides amagnetic shielding circuit since the flux lines extending through thealuminum ring create Eddy currents which produce opposing ampere turns.

Note also that the magnets which are positioned to be in rotor 13 inFIG. 1 can be anywhere in the flux path. For example, the pole pieces orthe steel of the timing ring, 12 could be magnets.

Another embodiment of the invention is shown in FIG. 6 wherein thetriggering coils are mounted on a spider 13A. The timing ring 12 and thepole pieces 37 and 39 function the same as in FIGS. 1 and 2. As shown inFIG. 6, the assembly indicated is adapted to provide triggering voltageto the spark plugs of the four cylinders of the associated engine.

Refer now to FIG. 7 for an understanding of the relative structuralorientation of the assembly of FIGS. 1, 2, 3, and 6. FIG. 7 shows onlyone pole piece 39, a portion of the rotor 13, trigger coil core 35 and aportion of coil 31. The trigger coil core 35 is positioned to beadjacent to the steel of the peripherally extending leg 47 of pole piece39 throughout the range of movement of the timing ring 12. Accordingly,regardless of the operating position of ring 12 (the two extremepositions being indicated by FIGS. 1 and 7), leg 47 is always adjacentthe trigger coil 35 thereby providing a precise accurate control of thefiring point of the engine, and a more uniform firing spark. Note thatthe rotor 13 and its firing point A rotates along a path flux conductorsection 49 of pole piece 39. Firing will occur when point A moves pastedge T on flux conductor section 39. Obviously, by moving the timingring 12 and hence pole piece 39, the firing point will be advanced orretarded relative to the rotation of rotor 13, causing the firing pointof the spark plug to be changed.

A modification of the pole piece 39 of FIG. 7 is shown in FIG. 8 whereinthe pole piece is labeled 39A. Pole piece 39A forms an inverted T-shape,and is positioned in the same relative relation as the L-shaped polepiece 39 of FIG. 7. In FIG. 8, the trigger coil core 35 is positionedoutwardly of pole piece 39A.

In FIG. 8, the peripherally extending leg 47A is relatively longer thanthe peripherally extending leg 47, of FIG. 7 and hence leg 47A willpermit a greater movement of the associated timing ring 12 while stillmaintaining a portion of the leg 47A at a position adjacent the triggerpin 35.

FIG. 9A shows another modification of the pole piece and trigger coilcore pin structure of the invention wherein the pole piece 393 comprisesan axially elongated, rectangularly shaped, member and the trigger coilcore 35A comprises a T-shape with the pole shoe portion 47] of theT-shape extending adjacent the periphery of the associated ring. Note inFIG. 93 that an air gap 36A is formed between the bottom surface of polepiece 398 and the trigger coil core 35A. In FIG. 9A the rotor (notshown) would be positioned as indicated in FIG. 7 to pass adjacent theupper portion of the pole piece 398.

Another modification of the pole piece and trigger coil core structureof the invention is shown in FIG. 9C wherein the pole piece 39A issimilar to that shown in FIG. 8; however, in the modification of FIG. 9Cthe trigger coil core 358 is positioned relatively underneath thehorizontally extending leg 47A of pole piece 39A.

Note, of course, that the terms vertically, horizontally etc., are usedfor relative reference purposes when explaining the figures and specificlimitation to these orientations is not intended.

As shown above, the embodiments of the pole pieces disclose an L-shape,a T-shape and a rectangular struc ture; however, other pole piece shapescan conceiveably be utilized. It should be understood, that a basicconcept of the invention is that the ferromagnetic portion of the timingring remains adjacent pole shoe of a pole piece at all positions of theengine advance or retard. Thus, the air gap between the timing ring andthe magnetic pole piece remain essentially constant; or varies in adefinite controlled manner as will be explained. The timing ring ispositioned such that the break or trigger point of the rotor relates tothe timing ring at the proper ignition or firing point for eachcylinder.

As also stated above, a feature of the present invention is that acommon timing ring can be used for two or four cylinder engines.Further, with modification, the timing ring can be used with a threecylinder engme.

FIG. shows an embodiment of the invention for use with an engine havingthree cylinders. In FIG. 10A the pole pieces are formed in a T-shapewith the pole pieces 39F and 39G being essentially as shown in FIG. 8;and, being placed at 0 and 120 respectively. The third pole piecelabeled 39H is positioned at approximately 270. Pole piece 39H has itsaxial leg 49H positioned at a point displaced from the center of theperipherally extending leg 47H. The offset of axial leg 49H has beenfound convenient for providing a necessary adjustment for a threecylinder engine. FIG. 108 shows another embodiment of the invention foruse with an engine having three cylinders. In this instance, the rotor138, having three arms is rotated by three L- shaped pole pieces 39.],39K, and 39L positioned at 0, 120, and 240 respectively.

FIG. 14 indicates an embodiment of the invention having pole pieces forthe timing ring which are adjustable in position as well as in shape.For explanation purposes, the pole pieces of FIG. 14 are depicted alonga linear graph which indicates circumferential degrees In FIG. 14 thepole pieces 39D, 41D, 37D and 43D are shown as having an L-shape andhaving adjustable axial flux conductor sections 49D of pole piece 39Dmay be adjustably positioned along the peripherally extending pole shoe47D from an extreme position on the left side (as oriented in FIG. 14)to a position on the right side of the leg 47D. In this manner, thetiming ring, such as that of FIG. 6, can be made common for 2, 3, and 4cylinder engines.

For a four cylinder engine, the four pole pieces the axial fluxconductor section of each of the pole pieces is at the left side of theperipherally pole shoeand the four pole pieces are located at 0, 90,180, and 270 respectively.

For a two cylinder engine, two pole pieces are used and the axial fluxconductor section of each of pole pieces is positioned at the leftsideof the peripherally extending pole shoe 47D; and, the two polepieces are located at the 0 and 180 respective positions of theassembly.

For a three cylinder engine, three pole pieces are used and the axialflux conductor section of, say 49D, of one pole piece (say 39D) islocated at the left edge of the peripheral pole shoe 47D. The axial fluxconductor section 49E of the second pole piece 41D is positioned to haveits center approximately two-thirds of the distance from the left edgeof peripheral pole shoe 47E; and, the axial flux conductor section ofthe third pole piece 37D is positioned at the left edge of theperipheral pole shoe; and, the pole pieces are positioned at the 0, and240 respectively.

Slots or recesses are formed in timing ring 12 into which the moveablepole pieces can be adjustably placed.

As shown in FIGS. 1, 2, 3, and 6, the pole pieces indicated are mountedto be a fixed distance from the trigger coil core. In most assemblies,this is the desired construction. However, for some applications, amodified positioning of the pole piece is useful. More specifically,depending on whether the peripherally extending pole shoe 47 of the polepiece is useful. More specifically, depending on whether theperipherally extending pole shoe 47 of the pole piece 39 is formed orpositioned to gradually increase the spacing between the inner surfaceof the trigger coil core 35 and the outer surface of the pole piece(measured along the length of the pole piece movement past the triggercoil core) the amount of advance for a given speed can be pre-selected.

As indicated in FIG. 12, the magnetic pole pieces, generally labeled39L, can be constructed to have a uniform spacing between the coil pin35 and the outer surface of the peripherally extending pole shoe of apole piece; or, each pole piece can be arranged to have a graduallyvarying spacing between the surface of the pole shoe and the triggercoil core 35. In FIG. 12, the solid line A indicates a uniform spacingbetween the pin 35 and the magnetic pole piece 39A; line B indicates agradually decreasing spacing and line C indicates a gradually increasingspacing. The curves of the graph of FIG. 13 show the change in thevoltage output relative to the advance with the pole piece 39L in therespective positions indicated in FIG. 12.

FIG. 11 depicts two important features of the invention, the firsthaving been mentioned hereinabove. This one feature indicated by thelight solid line in FIG. 11 relates to the fact that as the throttle ismoved toward a higher speed position, the timing ring 12 of FIG. 11 willbe moved to advance the timing cycle. As the timing is advanced thevoltage produced by the output coils will decrease and be less than whatis required to fire the engine. As stated, this is an important safetyfeature to prevent the engine from starting unless the throttle is at anidle or slow speed position.

Another feature of the invention indicated in FIG. 11 is that the timingring 12 of FIG. 1 enables the advance and speed characteristics of theengine to be adjusted to provide a uniform voltage output from thecoils. This is indicated by the heavy solid line in FIG. 11 which ineffect combines the speed curve indicated by the dotted line and theadvance curve indicated by the light solid line.

Still another feature and advantage of the present invention is depictedin FIG. 1 which indicates the mechanical linkage 18 of the timing ring12 to the associated throttle. The throttle linkage arrangementgenerally labeled 52 is such that as the throttle is moved from an idleposition toward its high speed position, the timing ring 12 is moved toadvance the firing point. At a selected point past the angle 0 (and asis known in the art). farther movement of the throttle toward a maximumspeed condition will cause a relatively reverse movement of throttlelinkage to move the timing ring 12 back toward a reduced advanceposition. It has been found that for speeds above a selected point. saythe crusing speed ofthe engine, the engine operates in a superior mannerif the advance is reduced.

While the invention has been particularly shown and described withreference to preferred embodiments thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the spirit and scope of theinvention.

What is claimed is:

l. A timing mechanism for a breakerless ignition systern, comprising. incombination, a rotor, means for providing a magnetic flux field, a fluxresponsive means including a triggering coil, a triggering core for thecoil, a mechanically adjustable element movable to a selected angularposition relative to said triggering core, magnetic pole piece meansmounted with said element. said pole piece means including a fluxconductor section and a pole shoe section, said rotor including adiscrete triggering point on its periphery, said rotor moving past theflux conductor section and thereby developing a triggering signal, themanually adjustable element being movable to move the pole piece means,and said pole piece means when moved being effective to change the pointat which triggering occurs, while still s justable element comprises aring mounted intermediate said triggering core for the coil and therotor, and wherein flexing of the electrical wires connected such as tothe coil is eliminated.

3. A timing mechanism as in claim 1 wherein said adjustable elementcomprises a timimg ring of a nonmagnetic material and the pole piecemeans are embedded therein.

4. A timing mechanism as in claim 1 wherein said pole piece means arearranged such that relative movement thereof changes the effective airgap between the rotor and the trigger core for the coil as a function ofthe angular position of said adjustable element.

5. A mechanism as in claim 1 wherein said means for changing saidtriggering point comprise an arcuate pole shoe having a portion defininga variable air gap between the rotor and said shoe, and said mechanismmeans for moving said pole piece relative to the periphery of saidrotor.

6. A timing mechanism as in claim 1 wherein the flux conductor sectionextends to a position for maximum interaction with said rotor and saidpole shoe remains in a position for maximum interaction with saidtrigger core for the coil.

1. A timing mechanism for a breakerless ignition system, comprising, incombination, a rotor, means for providing a magnetic flux field, a fluxresponsive means including a triggering coil, a triggering core for thecoil, a mechanically adjustable element movable to a selected angularposition relative to said triggering core, magnetic pole piece meansmounted with said element, said pole piece means including a fluxconductor section and a pole shoe section, said rotor including adiscrete triggering point on its periphery, said rotor moving past theflux conductor section and thereby developing a triggering signal, themanually adjustable element being movable to move the pole piece means,and said pole piece means when moved being effective to change the pointat which triggering occurs, while still maintaining a section of thepole shoe adjacent said triggering core so as to develop a triggervoltage of a selected amplitude.
 1. A timing mechanism for a breakerlessignition system, comprising, in combination, a rotor, means forproviding a magnetic flux field, a flux responsive means including atriggering coil, a triggering core for the coil, a mechanicallyadjustable element movable to a selected angular position relative tosaid triggering core, magnetic pole piece means mounted with saidelement, said pole piece means including a flux conductor section and apole shoe section, said rotor including a discrete triggering point onits periphery, said rotor moving past the flux conductor section andthereby developing a triggering signal, the manually adjustable elementbeing movable to move the pole piece means, and said pole piece meanswhen moved being effective to change the point at which triggeringoccurs, while still maintaining a section of the pole shoe adjacent saidtriggering core so as to develop a trigger voltage of a selectedamplitude.
 2. A timing mechanism as in claim 1 wherein said adjustableelement comprises a ring mounted intermediate said triggering core forthe coil and the rotor, and wherein flexing of the electrical wiresconnected such as to the coil is eliminated.
 3. A timing mechanism as inclaim 1 wherein said adjustable element comprises a timimg ring of anon-magnetic material and the pole piece means are embedded therein. 4.A timing mechanism as in claim 1 wherein said pole piece means arearranged such that relative movement thereof changes the effective airgap between the rotor and the trigger core for the coil as a function ofthe angular position of said adjustable element.
 5. A mechanism as inclaim 1 wherein said means for changing said triggering point comprisean arcuate pole shoe having a portion defining a variable air gapbetween the rotor and said shoe, and said mechanism means for movingsaid pole piece relative to the periphery of said rotor.